Search Results (268)

Enterococcus lactis KUST2812 is a halotolerant strain isolated from broad bean paste (BBP). It shows strong potential as a safe fermentation starter due to its high survival rate (98.32% in 18% NaCl), absence of hemolytic activity, and susceptibility to clinically relevant antibiotics, with resistance limited to intrinsic traits. Growth and metabolic dynamics suggest that salt stress decouples growth from tyrosine catabolism: while 6% NaCl significantly inhibited bacterial cell growth, tyrosine depletion occurred within 12 h under 6% NaCl, compared with the 96 h required under non-saline conditions. Multi-omics analyses suggest a molecular network associated with this tyrosine conversion under salt stress. Two tyrosine decarboxylase genes (tdc) were upregulated by 1.85- and 6.50-fold, respectively. The tyrosine-specific transporter gene tyrP was upregulated 4.99-fold, and the protein synthesis-associated gene tyrS was upregulated 4.93-fold. These changes collectively support a diversified tyrosine utilization strategy of E. lactis KUST2812. Moreover, coordinated responses involving the Na⁺/H⁺ antiporter system, compatible solute transporters, and oxidative stress markers contributed to the metabolic basis for salt adaptation of this strain. Evaluation in BBP fermentation suggested that E. lactis KUST2812 may reduce tyrosine accumulation without causing a significant increase in tyramine. These findings offer a potential microbial resource and a theoretical basis for managing tyrosine-related quality issues in fermented foods. Full article

Cocoa fermentation is a critical postharvest process that determines the physicochemical and sensory quality of cocoa beans through complex microbial and biochemical transformations. This study evaluated the effect of selected lactic acid bacteria (LAB), i.e., Weissella confusa and Lactiplantibacillus plantarum, and the fermentation system on the fermentation dynamics and final quality of two cocoa genotypes (i.e., Theobroma cacao L.; Nacional and CCN-51). A completely randomized 2 × 2 × 2 factorial design was applied, considering cocoa genotypes, LAB species, and fermentation system (i.e., laboratory fermentation and cascade-type box fermentation). During fermentation, pH, temperature, and total soluble solids (°Brix) were monitored at 0, 24, 48, and 72 h. In addition, cut test parameters and the physicochemical properties of the final cocoa paste were evaluated. The results showed a progressive decrease in pH (from 3.13 to 4.17), accompanied by a temperature increase up to 46.50 °C and a marked reduction in soluble solids during the final fermentation stages, reflecting intense microbial metabolism and substrate utilization. Treatments inoculated with L. plantarum achieved the highest proportion of well-fermented beans (up to 93.73%), indicating enhanced fermentation performance. Furthermore, the physicochemical properties of the final cocoa paste, including moisture, fat, ash, pH, and °Brix, were significantly influenced by the interaction among cocoa genotype, LAB species, and fermentation system. Overall, controlled fermentation using selected LAB species represents a promising biotechnological strategy for improving cocoa fermentation consistency and enhancing postharvest cocoa quality. Full article

Bioactive peptides (BPs) are increasingly recognized for modulating the gut microbiome, metabolome, and brain function via the gut–brain axis. Kapi-pla, a traditional Thai fermented freshwater fish paste rich in proteins and peptides, is widely consumed in Southern Thailand. This study profiled the peptides of Phatthalung Kapi-pla (PK) and Songkhla Kapi-pla (SK) and investigated their impacts on gut microbiota and metabolome using a simulated colonic fermentation model with fecal samples from patients with Alzheimer’s disease (AD). Microbial composition and metabolites were assessed by 16S rRNA sequencing and LC–MS/MS, respectively. After 24 h fermentation, PK modestly increased Shannon diversity relative to the unsupplemented control, with richness indices unchanged, reduced Proteobacteria abundance and opportunistic pathogens such as Escherichia–Shigella and Klebsiella, and selectively increased short- and branched-chain fatty acids, including acetate, propionate, butyrate, and iso-valerate. PK further enhanced neuroactive metabolites relevant to AD pathology, underscoring its potential as a functional food ingredient to ameliorate AD-associated dysbiosis and support gut–brain axis health. Full article

This research investigated the effects of salt concentration on the fermentation of watermelon soybean paste. Three experimental groups were constructed with gradient salt concentrations, and multi-dimensional analyses were performed on physicochemical properties, volatile aroma profiles, and microbial community succession throughout the fermentation process. Group X (lowest salt) exhibited the highest total acid (34.49 g/kg) and lowest pH (p < 0.05) after 60 d. Using headspace gas chromatography time-of-flight mass spectrometry (HS-GC-TOF-MS), a total of 97 volatile compounds were identified, of which 18 were defined as key flavor compounds (relative odor activity value (ROAV) > 0.1 and variable importance in projection (VIP) > 1). High-throughput sequencing demonstrated that Proteobacteria and Firmicutes represented the core bacterial communities while Ascomycota emerged as the dominant fungal phylum. The Shannon diversity index for bacteria ranged from 4.28 to 5.47 across groups. Aspergillus relative abundance in Group X decreased from 75.30% (30 d) to 43.17% (60 d). Group X was distinctly separated from Y and Z in PLS-DA and PCoA analyses. Aspergillus exhibited significant positive correlations with eugenol and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (p < 0.05). These findings provide an integrated understanding of the associations between volatile compound evolution and microbial succession during natural fermentation, providing a basis for further investigation and process optimization. Full article

Acetate is emerging as an influencer of wellbeing. The interest in acetate parallels the mounting reports of preclinical and small-scale clinical investigations over the past two decades suggesting the health benefits of vinegar, a dietary source of acetic acid along with fermented and pickled foods. Additionally, acetic acid is generated during fermentation by the gut microbiome and is considered a main benefit of the gut microbiome. However, numerous factors adversely impact acetic acid production by gut microbiota such as medications, disease states, and low fiber intakes. Since acetic acid rapidly deprotonates when entering the blood stream, it is a source of systemic acetate. A third source of acetate is endogenous production by various tissues via deacetylation reactions, and endogenous acetate production is 2-fold that generated by microbiota fermentation. This narrative review highlights acetate metabolism and impacts on health parameters as well as the role of vinegar in health promotion as an exogenous source of acetic acid. Full article

Lactic Acid Bacteria (LAB) and other starter cultures play key roles in fermented meat products by influencing fermentation, safety, sensory properties, and metabolite formation. Metabolomic approaches based mainly on mass spectrometry, including GC-MS, LC-MS, and CE-MS, as well as nuclear magnetic resonance (NMR), provide useful tools for characterizing volatile and non-volatile metabolites, monitoring quality, and identifying candidate biomarkers. This narrative review summarizes recent studies from the past seven years on metabolomic approaches applied to fermented meat products, with emphasis on LAB, starter cultures, and metabolites related to quality, safety, and fermentation. Overall, metabolomics can support the holistic characterization of fermented meat products and improve understanding of microbial activity during fermentation and ripening. Full article

This study investigated the effects of microwave puffing-induced soy protein structural modification on the dynamic changes in physicochemical properties and umami formation during soybean paste fermentation. The results indicated that optimal microwave puffing (400 W, 90 s) disrupts protein non-covalent bonds, depolymerizes protein aggregates, exposes the internal hydrophobic groups to enhance surface hydrophobicity, forms a loose porous structure, and creates favorable conditions for enzymatic hydrolysis during soybean paste fermentation. Conversely, excessive treatment (400 W, >90 s) induced protein re-aggregation and inhibited proteolysis, as confirmed by SEM. Furthermore, microwave puffing (400 W, 90 s) promoted Aspergillus oryzae growth and protease activity, and significantly improved physicochemical properties of soybean paste, including lower pH and higher contents of total acid (5.8%), amino acid nitrogen (11.8%), small peptides (13.3%), and reducing sugars (14.95%) (p < 0.05), plus a brighter, redder color. LC-MS/MS revealed microwave puffing (400 W, 90 s) reshaped the peptide profile of soybean paste, increasing the relative abundance of the umami amino acids (Glu, Asp) and sweet amino acid (Ala) and decreasing proportions of the bitter amino acids in the peptides. Sensory and electronic tongue analyses confirmed enhanced umami and weaker bitterness and saltiness. These findings demonstrate that microwave puffing (400 W, 90 s) effectively improves the quality and flavor characteristics of soybean paste, providing technical support for high-quality fermented soybean products. Full article

The prebiotic concept now extends past inulin and fructo-oligosaccharides to diverse dietary compounds for selective gut microbial utilization and health promotion. This review explores Pleurotus eryngii as a source of prebiotic substrates, with a focus on how preparation methods and molecular traits affect its digestive stability, fermentability and food applicability. The tested materials include various mushroom-derived fractions: polysaccharides (native and modified), β-glucan extracts, powders, hydrolysates, protein co-extracts, exopolysaccharides and composite matrices. Many fractions survive upper gastrointestinal digestion and produce short-chain fatty acids whose profiles vary with the substrate during fecal fermentation. Animal studies have demonstrated their positive impacts on intestinal barriers, immunity and metabolism, and these ingredients fit well into multiple food formulations. Rather than treating Pleurotus eryngii as a uniform polysaccharide product, evaluations should be performed for each individual preparation. Existing data supports Pleurotus eryngii as a promising source of structurally diverse candidate prebiotic substrates, with a consistent biological rationale linking digestive persistence, microbial fermentation, short-chain fatty acid production, microbiota modulation and gut-related host responses. Further research is required to verify the microbiota-related causal mechanisms, assess finished food products and implement human microbiota intervention trials. Full article

To address the issues of rough mouthfeel and monotonous flavor in plant-based beverages, this study used extruded millet flour as the raw material, with non-inoculated millet paste as the control group, and investigated the effects of six different lactic acid bacteria starter culture formulations—including two single strains (Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) and four multi-strain consortia (2, 4, 10, and 12 strains)—on the quality of fermented millet beverages. The structural properties of the fermented millet beverages were systematically evaluated through WHC (Water Holding Capacity), LF-NMR (Low-Field Nuclear Magnetic Resonance), RVA (Rapid Visco Analyzer), rheological properties, texture, particle size, and FTIR (Fourier Transform Infrared) analyses, covering aspects such as water status, pasting behavior, viscoelasticity, textural characteristics, particle distribution, and molecular structure. In combination with volatile flavor profiling and sensory evaluation, the fermentation performance and applicability of each starter formulation were comprehensively assessed. The results showed that MFB-2 exhibited the highest viscosity and gel strength, making it suitable for thick-set products, whereas MFB-10 and MFB-12 demonstrated superior gel stability, water-holding capacity, and shelf life. Sensory evaluation further corroborated the flavor analysis, with MFB-12 showing the best aroma and overall acceptability, alongside the greatest diversity of volatile compounds, while MFB-10 presented milder acidity and favorable sensory acceptability. Collectively, MFB-10 and MFB-12 were identified as the most promising starter culture formulations for industrial-scale production of fermented millet beverages. This study provides a scientific basis for tailoring starter culture complexity to modulate the texture and flavor of plant-based fermented products. Full article

Pixian Doubanjiang (PXDB) is a traditional Chinese fermented condiment whose characteristic aroma and taste are strongly influenced by fermentation conditions. This study aimed to systematically compare the flavor profiles of PXDB produced via traditional open fermentation (TOF) and industrial closed fermentation (ICF), aiming to elucidate the chemical basis of sensory divergence and provide scientific support for industrial process optimization. In this study, PXDB samples were evaluated using sensory evaluation, GC-IMS, ¹H-NMR metabolomics, and multivariate statistical analysis. Sensory evaluation revealed that ICF exhibited a stronger soy sauce-like aroma, alcohol note, and umami intensity, whereas TOF and ICF showed comparable sweetness, sourness, chili-like aroma, and roasted aroma. GC-IMS putatively identified 126 volatile compounds, and multivariate analyses demonstrated a clear separation between the two fermentation modes. Based on combined criteria of VIP > 1, FDR-adjusted p < 0.05, and |fold change| > 2, 35 differential volatile compounds were identified. ICF was characterized by higher levels of esters, particularly ethyl esters, and selected ketones, while TOF showed enrichment of higher alcohols, terpenes, and sulfur compounds. ¹H-NMR analysis identified 54 non-volatile metabolites, of which 16 differed significantly between TOF and ICF, mainly involving amino acids, organic acids, and carbohydrates. Pathway analysis highlighted branched-chain amino acid and glutamate-related metabolism as key contributors to flavor divergence. Correlation analysis further revealed that soy sauce-like aroma and umami perception were strongly associated with amino acid-derived metabolites, esters, sulfur-containing compounds, and branched-chain aldehydes, highlighting the coordinated contribution of volatile and non-volatile compounds to flavor differentiation. Overall, fermentation mode was found to reshape PXDB flavor through coordinated modulation of volatile and non-volatile metabolism, providing experimental insight for improving industrial fermentation quality. Full article

Stir-frying is an important process for terminating fermentation and improving the flavor of sour shrimp paste. This study investigated the flavor characteristics, volatile profiles, and post-storage microbial community of stir-fried sour shrimp paste. Sensory evaluation demonstrated that it exhibits a well-balanced flavor profile, characterized by fruity, soy sauce, spicy, and salty notes. Based on HS-SPME-GC-MS analysis, a total of 68 volatile compounds were identified, of which 26 made notable contributions to the aroma. Among them, esters were the most diverse group, with ethyl butyrate, ethyl acetate, and ethyl 2-methylbutyrate serving as the main contributors to the fruity aroma. Acids such as butanoic acid, acetic acid, and 2-methylbutanoic acid far exceeded their thresholds, linking to sour and spicy notes. Microbial community analysis revealed that low-abundance fermentative bacteria, such as Vagococcus and Levilactobacillus, remained detectable after storage, whereas Pseudomonas and Acinetobacter were identified as the most probable spoilage organisms. These findings provide a systematic understanding of the unique flavor of stir-fried sour shrimp paste and its potential microbial risks during storage, providing a basis for the application of stir-frying technology. Full article

The aim of this study was to investigate the dynamic changes in physicochemical properties, microbial community, metabolite profiles, and volatile compounds in watermelon soybean paste (WSP) during natural fermentation. Results showed that total acids, amino nitrogen, reducing sugar content, and umami-taste amino acids were significantly increased in WSP samples during the fermentation process. Various bacterial communities, including Enterobacter, Bacillus, Staphylococcus, Enterococcus, Weissella, and Lactobacillus, were detected as dominant genera. A total of 804 metabolites, mainly including lipids (18.78%) and amino acids and their derivatives (13.56%), were detected across the different fermentation stages. The correlation analysis between volatile compounds and bacterial community at the genus level revealed that 2-methylisoborneol, 1-octen-3-ol, benzene acetaldehyde, tetramethylpyrazine, and phenylethyl alcohol strongly correlated with Enterococcus, Bacillus, Weissella, and Pseudomonas. This study revealed the dynamics of the bacterial community and volatile compounds in the fermentation process and demonstrated their inter-relationship during WSP fermentation. Full article

Few strategies have been developed to mimic and control the supramolecular degradations induced by spontaneous fermentation in sour cassava starch, which are partly responsible for its characteristic expansion capacity in breadmaking, and their effectiveness has remained limited. In this context, the objective of this study was to evaluate the effect of adding α-amylase on the functional and nutritional properties of cassava starch used in breadmaking. Cassava starch from the INIAP 651 variety was modified with different α-amylase dosages (0, 2, 4, 6, 8, and 9 U/g α-amylase for 20 min), followed by hydration and pre-gelatinization before baking. Determinations of the specific volume of the bread (SV), dough characterization by Mixolab, pasting properties using a rheometer, and nutritional properties were performed. The treatment with 6 U/g α-amylase showed the best functional properties, achieving the highest SV (4.28 mL/g), C3 (1.67 Nm), C4 (1.11 Nm), and peak viscosity (6550 mPa·s), as well as the lowest setback (1526 mPa·s). In contrast, the treatment with 9 U/g α-amylase exhibited the most favorable nutritional profile, with the lowest estimated glycemic index (51.25) and rapidly digestible starch (15.85 g/100 g). These results confirm that controlled α-amylase dosing modulates cassava starch functionality for breadmaking and glycemic control. Full article

Large-scale production of Bacillus thuringiensis, one of the most widely used biopesticides, is often limited by the high cost of conventional culture media. In this study, fermented cassava paste water (EFM), ripe mango pulp juice (CM), and cashew apple juice (JPC) were evaluated as alternative substrates for the liquid fermentation of B. thuringiensis var. kurstaki HD-1. Physicochemical analyses revealed acidic pH values and classified the substrates into two clusters: CM with high C/N ratios, organic matter, total sugars, and proteins, and EFM and JPC with lower C/N ratios and nutrient levels. Fermentation results indicated that JPC supported the highest biomass production (8.29 × 10¹³ CFU mL⁻¹), exceeding that in the standard Tryptone Soy Broth (TSB) medium. However, CM promoted the highest sporulation rate (1.46 × 10¹³ CFU mL⁻¹) and the greatest bioactive lipopeptides—iturins (102.2 mg L⁻¹) and surfactins (554.7 mg L⁻¹)—surpassing TSB. The antifungal activity of crude fermented CM, EFM, and TSB was evaluated against Sclerotium rolfsii. All samples significantly inhibited mycelial growth of the pathogen with no significant differences among substrates or concentrations tested. This study highlights the potential of B. thuringiensis-fermented agrowaste as a cost-effective, environmentally friendly biocontrol tool for Sclerotium rolfsii. Full article

This study investigated how three chili pepper varieties (Huanggong, millet, and long slender) affect fermentation dynamics, flavor formation, and microbial succession in spontaneously fermented chopped chili. Physicochemical analyses, sensory evaluation, GC–MS, electronic tongue analysis, and high-throughput sequencing were employed to characterize quality attributes, volatile flavor profiles, and microbial structures during the process. The results demonstrated that chili pepper variety significantly influenced fermentation behavior (pH range: 4.07–4.26; total acidity: 5.68–7.69 g/kg) and quality. Distinct differences were observed in acidification patterns, substrate utilization, sensory characteristics, and optimal fermentation stages Volatile flavor analysis revealed that chopped chili peppers produced from different varieties exhibited differentiated aroma profiles while sharing a common flavor framework composed of several key aroma-active compounds. Microbial community analysis indicated that the chili pepper variety drove distinct microbial succession patterns during the process, and dominant microbial groups showed significant correlations with the formation of specific flavor compounds. Overall, these findings demonstrate that chili pepper variety regulates flavor and quality formation in chopped chili peppers by modulating microbial community structure and metabolic activity, providing a scientific basis for raw material selection and targeted flavor control in fermented chili products. A total of 63–68 volatile compounds were identified across varieties, with OAV > 1 for 11–24 compounds. Three biological replicates were analyzed per time point. Full article